1. Field of the Invention
The present invention relates to low-dropout regulators, and more particularly, to a low-dropout regulator that can prevent a metal-oxide-semiconductor field-effect transistor (MOSFET), applied to the lower-dropout regulator, from operating in a triode or deep triode mode.
2. Description of the Related Art
Low-dropout regulators are being used in the voltage supply circuits of electronic applications in various fields ranging from laptop computers to mobile communications terminals. A low-dropout regulator may be used when a specific load of an electronic device cannot directly use a power voltage, being provided from the outside, or the quality of the power voltage is not uniform. A low-dropout regulator outputs a controlled voltage in which the power voltage undergoes a low voltage drop.
Recently, research has been actively conducted into voltage and current-supply circuits using CMOS technologies. In particular, analog control blocks are in development in order to ensure the stability of circuit operations. The above-described low-dropout regulator is a type of analog control block and is manufactured using a CMOS process. Analog control blocks using this CMOS process require more accurate and stable control than existing circuits. In particular, an analog control block, that is, transistors, included in a low-dropout regulator, perform stable and rapid operations when operating in a saturation region. However, depending on operation schemes, the transistors may operate in the triode or deep triode region, which causes a reduction in the operation speed of the circuit and a decrease in stability. Therefore, there is a need for an improved circuit design method capable of preventing transistors, included in an analog control circuit, in particular, a low-dropout regulator, from operating in the triode or deep triode region.